Novel biogenesis and function of small RNAs derived from a plant pathogen

在基因表达过程中，RNA在将遗传信息从DNA转移到蛋白质中起着重要作用，这是植物或动物生长发育的关键。近年来的研究发现，RNA本身除了参与蛋白质合成外，还有许多新的生物学作用。一些rna可以控制某些基因的表达，这些基因对许多生物体的发育和生理很重要。植物病毒和类病毒在感染过程中产生的大约20个核苷酸的小rna被认为指导宿主防御系统抑制这些病原体的复制。据推测，来自植物病毒和类病毒的一些小rna也可以调节选择性宿主基因的表达，从而促进感染和引起疾病。这一新概念意味着病毒病原体不仅使用蛋白质，而且还使用小rna来操纵宿主代谢以实现感染。这一假设将通过研究马铃薯纺锤体块茎类病毒在感染过程中衍生的小rna的形成和功能作为模型系统来验证。结合遗传和生化实验将用于确定产生这些小rna的分子途径。进一步的生化和分子实验将确定这些小rna是否可以调节选定宿主基因的表达，以及宿主基因表达的改变是否有助于症状的发展。这些研究结果将为进一步了解植物病原体如何在被感染植物中完成感染并引起疾病提供重要信息。它们还可能为研究RNA在动物和人类感染病毒过程中的作用提供有用的信息。最后，这些结果可能为开发新的基于rna的工具来研究植物基因功能提供有价值的线索。

RNA plays an important role in transferring genetic information from DNA to protein during gene expression that is key to growth and development of a plant or animal. Recent studies have discovered that RNA itself has many novel biological roles apart from participating in protein synthesis. Some RNAs can control the expression of certain genes that is important for development and physiology of many organisms. Small RNAs of approximately 20 nucleotides produced from plant viruses and viroids during infection are believed to guide a host defense system to suppress the replication of these pathogens. It is hypothesized that some small RNAs derived from plant viruses and viroids can also regulate expression of selective host genes to promote infection and cause diseases. This novel concept implies that viral pathogens do not only use proteins, but also use small RNAs, to manipulate host metabolism to achieve infection. This hypothesis will be tested by investigating the formation and function of small RNAs derived from Potato spindle tuber viroid during infection as a model system. Combined genetic and biochemical experiments will be used to determine the molecular pathway that produces these small RNAs. Further biochemical and molecular experiments will be conducted to determine whether these small RNAs can regulate the expression of selected host genes and whether altered expression of a host gene contributes to symptom development. Results from these investigations will provide important information to advance understanding of how plant pathogens accomplish infection and causes diseases in an infected plant. They may also provide useful information to study the role of RNA during infection of animals and humans by viruses. Finally, the results may provide valuable clues to develop novel RNA-based tools to study gene functions in plants.